Patent GB-190626998-A (GB)
Title: Improvements in Automatic Electric Car Brakes.
Inventor: MCCOLLUM JAMES HARRY KEIGHLY
Filed: 1906-11-27
Granted: 1907-05-30
Abstract: 26,998. McCollum, J. H. K. Nov. 27. Switches.-Relates to an electrically-controlled brake which is normally applied by springs and which is held off by a magnet. Figs. 1 and 2 show one car equipment in plan and perspective views, and Fig. 3 shows the circuits for three coupled cars. The brake beam C is coupled by a link I to a lever G, which is pivoted to the framing at G<1> and is moved to the right by a compression spring J<5> to apply the brakes, and to the left by the armature 2 of the magnet H<1> to release them. The brakes are locked in the released position by a band brake 0, magnetically operated by a magnet P so as to control the rotation of an horizontal ratchet-wheel G<6>. The spindle G' on which this wheel turns carries a pair of pawls G<8> and a pinion G3, which engages a rack G<2> pivoted to the lever G. The spring J<5> is compressed by a motor M<5> and spindle M, which is worm-geared to the screwed extremity K of the outer spring rods J<4> . The wires 10, 11 are connected to the line and return, respectively, and 12, ,13 are auxiliary wires for connexion to the line when the magnet H<1> and the motor M<5> and magnet P are to be energized, the return circuits for these three being through the wires 12<4>, 15<4>, 15<2>, An additional line conductor 14 is connected to the wire 13 of the last carriage by a loop 15, and carries a series of knife switches 9, the blades of which are mounted on beams suspended just above the rail level so as to be lifted in order to break the circuit should any car become derailed. For ordinary running, the controller handle Q<5> is so placed as to connect the fingers T<2>, T3 together by the coupled contacts Q<3>. This brings the line pressure by way of the conductors 10<2> to the motor M<5> and the magnet P, so that the spring J<5> is compressed. The brakes, however, cannot be applied, as the rack G' and wheel G<3> are locked by the engagement of the pawls and braked ratchetwheel G<6>. To apply the brakes, the controller is shifted so as to disconnect the trolly from the line, and so to de-energize the magnet P and motor M<5>. The spring J<5> is thus free to apply the brakes, the rack G<2> driving the pawls and freed wheel G3 bodily, and the screw K driving the worm-wheel, spindle M, and motor armature until arrested by the abutment of the outer nut K<2> on the stop L. To release the brakes, the controller is placed as shown in Fig. 2, so that the line pressure passes from the wire 10<2> through the contacts Q<2> and . fingers T to the magnet H<1>. The armature and rack G<2> are thus drawn back, the pawls G riding over the teeth G<6> The band O may be operated mechanically as shown in Fig. 6, the magnet P for applying the brake being replaced by a compression spring V, and the lever Q<5> being attached to an arm V<1> on the controller spindle, the motion of which releases the band. The controller carries a projection which, in the extreme positions, bears on spring-pressed plungers R<1>, the spring resistance to motion of the handle encountered when the controller is in the releasing position being great, to remind the motorman of the position and also to move the controller back to the running position.